Scatter plot: Remove entities from the data table that are not displayed in the chart

[sophiamersmann]

Description

• Scatter plots often use population to size circles
• Entities that have no data for any year for the x- and y-dimension, but do have data for the size-dimension show up in the data table
• We would rather not list those entities in the table

Expected behaviour

Don't list entities that only have data for the size-dimension in the data table.

Steps to reproduce

1. Go to https://ourworldindata.org/grapher/gini-coefficient-after-vs-before-tax-wb-scatter
2. Note that Afghanistan is not displayed in the chart and is also not listed in the entity selector dialog
3. Note that the table lists Afghanistan as an entity

Screenshots

Additional context

This came up in the Grapher redesign bug bash.